Why do we have personalities?

So one obvious question is, if this is right– if I really am making up my mind as I go along, quite literally, just as a creative writer is making up the minds of their characters and inventing the story that they create– I’m inventing the story I’m living. If that’s really right– if it’s the case that my thoughts, my beliefs, desires are not hidden within me, but are being fabricated moment to moment, then why is it the case that I’m a stable creature at all? People seem quite similar from time to time. You meet them in different occasions, they seem very distinct and special and not confusable with each other.

They don’t seem to make wild lunges from one form of behaviour to another. Occasionally, people have great changes of heart, changes of lifestyle. But most of the time, we’re pretty consistent. How is it that we have a sense of stable human personality, stable lives, where at the heart, we’re essentially doing a kind of creative improvisational acting? Well, the answer, of course, is that each decision is not being made in isolation. When you pop someone in a lab, then they are all over the place. They’ll make wildly inconsistent decisions from one time to the next. They’ll make various crazy decisions which make no objective sense. But if you put them in the real world, they’re not making each decision separately.

They’re making decisions one by one, but in the context of all the previous decisions they’ve made and all the things other people do too. But of course, they also are working in the light of the expectations others have about them. So I know what you’ve seen me normally do. And I know you’ll be very surprised if I don’t behave in much the same way, so I feel I should behave in much the same way. And anyway, I probably will, because in deciding how to behave now, I’m naturally pushed in the direction of behaving in a way which is consistent with my previous behaviour. That fits the story.

Just as a creative writer doesn’t want their characters to drift all over the place and behave in wild out of character ways, which is very unsatisfying for the reader and the writer, in practice, the same story applies for us. To make a good story of our own lives, we want that life to be coherent. We want the goals that we live by to be relatively stable so we can achieve them. If our goals continually change– if one moment, it’s football stardom and at the next moment, it’s great success in music– then it’s unlikely I’ll achieve any of these goals. Similarly, if the people I like continually change, then it’s unlikely I’ll have successful social relationships with any of them.

And even at the level of a prosaic day to day activity, unless I have a story about what I’m trying to achieve today and stick more or less to that story, then I’ll find myself continually being diverted in random behaviours, being attracted by interesting looking places I might look round, interesting shops I might go into, interesting books I might pick up. And it will be impossible to live a coherent, effective life.

So we have stories running at every scale, from huge stories about why am I here, what are my values, what do I care about– these things are all relatively unstable, but they knit together– to local stories about, what am I doing this year, this month, today, at the moment. And these stories themselves are quite unstable. If I trick you by giving you false feedback, I can make you think you’re in a different story to the one you’re actually in. But most of the time, this doesn’t happen, and the stories that guide us interlock pretty well and we’re pretty stable creatures. But the thing that I want you to ponder is how this affects our perception of human personality.

A natural perspective on personality is to think we just have personalities and the personalities determine our behaviour. So the personality’s in there, and that just shapes the way we do things. But for the way I’m thinking about it– and this is your discussion point for the week– maybe it’s the other way around. Maybe it requires massive cognitive effort, continual thought and careful pondering about your behaviour past, present, and future to maintain a stable personality. Maybe actually having a stable set of values and goals and making your behaviour cohere across those values and goals, across long periods of time– maybe that’s really hard.

Maybe that’s, in fact, one of the crucial functions of the brain– to make our thoughts, behaviours, actions, and values cohere across time. So from this point of view, personality as a construct is a really hard construct. And if your brain ceases to think very carefully and actively about what you’ve done in the past, what your current plans are, what other people are doing, and shapes your future behaviour on the basis of that, without that, your personality will disintegrate quite fast.